Yes.
The organs of the circulatory system include the blood, blood vessels, and heart. The blood is an unusual organ in that it is a liquid.
entero-hepatic portal system
Possible yes probable no. Highly unusual after 18/19
Nose bleeds from exercise can be caused from a variety of factors. It is possible that you are having an acute increase in your blood pressure. Make sure that you are not holding your breath while you exercise, which tends to increase your inter thoracic pressure. You should check your blood pressure prior to and after a bout of exercise. Other cause may be medications, or allergies which irritate your mucous membranes. If your nose bleeds continue, I would definitely consult with your family physician.
The answer is the Hepatic Portal System.
A lack of light, and the increase atmosheric pressure
Not at all. Each of the four main blood vessels that connect the heart to the circulatory system has a valve within in it. It's not uncommon to need more than one valve replacing.
Platelets are little spheres that cruise the circulatory system, when they encounter something unusual, like the collagen OUTSIDE of the blood vessel, they transform and begin the clotting process.
To increase the ratio of distance propelled per pedaling revolution, a very large driven wheel was used.
It is not unusual for people to experience some soreness or stiffness after a session of bodywork or movement therapies, particularly if they have not been accustomed to regular physical exercise.
The Army wanted to increase its troop strength by 50,000 men for this War, and over 220,000 men volunteered.
more unusual, most unusual